Cameras are used to capture photographs in nearly every imaginable situation. For almost all purposes, that a photographer is present does not change the captured subject. For example, in landscape photography, a photographer can work in the open, position a camera on a tripod and wait for the perfect moment to capture a scene without negatively affecting the resulting photographs. Similarly, portrait photographers deliberately alter the poses and expressions of their subjects to achieve a desired outcome.
For photographers who take candid or “street” photographs, however, the mere presence of a camera can cause changes to the scene. Candid photographers usually desire to capture people “as they are” rather than influencing the outcome. Typically, when people see a camera, they deliberately smile and look at the camera or, alternatively, other people may walk away because they desire to avoid being photographed. For the candid photographer, what is needed is a way to capture candid photographs of people without altering the behavior of the subjects or their pose.